Yes, all solar panels are recyclable, regardless of whether they are silicon-based or thin-film panel types. Solar panels contain a number of recyclable materials including a glass cover, an aluminum frame, copper wiring and other materials.
A solar panel is a collection of photovoltaic (PV) cells arranged in a grid and held in place by a metal frame and glass cover. Each PV cell in a solar panel generates electricity in response to sunlight, but the output of a solar panel is determined by its power rating, not by the number of solar cells it contains. Silicon-based solar panels, made from one piece of silicon or several silicon crystals, are the most efficient type of solar panel.
The process of recycling panels is difficult, expensive, and time-consuming. In order to recycle silicon-based solar panels like monocrystalline and polycrystalline panels, they need to undergo a chemical treatment called etching to extract the pure silicon. In the case of thin-film panels, recycling them requires removing the semiconductor layers and shredding them in a specialized piece of equipment called a hammermill.
There are numerous steps in the solar panel recycling process. The first step is to remove the aluminum frame either manually using basic tools, or mechanically using an automated frame separator. The second step to recycle a solar panel is to separate the glass from the module by applying heat to melt the adhesive, applying physical pressure to the panel (crushing, grinding, vibration), or using a chemical treatment to dissolve the resin holding the layer of glass and the layer of solar cells together.
The third step in recycling a solar panel is thermal processing the solar cells at 900 degrees Fahrenheit to remove any remaining residue, isolating the silicon, before the fourth step of 'etching' silicon wafers from the cell using a chemical treatment.
Recycling solar panels has a positive effect on the environment insofar as it decreases the number of discarded PV modules in landfills and the amount of minerals being mined to produce virgin silicon. It is crucial that the solar industry has a circular economy, where components from end-of-life solar panels are reused, in order for it to be sustainable.
Additionally, recycling dead solar panels in the US keeps the valuable raw materials that they contain in circulation and decreases reliance on imports to meet the domestic demand for solar energy.
The only risk of recycling a solar panel is damaging the module in the process; there is a fine line between separating the components without damage and applying too much force. The ethylene-vinyl acetate (EVA), which holds the layer of a solar panel together, makes taking it apart a tricky task.
European regulations for solar panel recycling are incredibly forward-thinking, with a mandate in place that requires all photovoltaic manufacturers to recycle 75% of solar panel waste and recover 80% of the raw materials within them. On the other hand, in the United States, unusable solar panels are given the status of 'solid waste,' marked as hazardous, and sent to landfill.
Solar panel recycling falls under hazardous waste regulation in the US, which means that discarded PV modules are flagged as toxic (due to containing heavy metals) and sent to specialized units in landfills that house toxic waste to protect the groundwater.
General recycling facilities process glass, copper and aluminum, but there are only 26 solar panel recycling companies in the US recognised by the national Department of Energy to process the other solar panel components. Solar panel recycling is inaccessible and expensive in the US, in addition to the absence of legislation on the topic, so the majority of solar panels end up in landfill.
What is a Solar Panel?
A solar panel is a collection of photovoltaic cells arranged in a grid, encased by a metal frame and glass cover, and used to generate electricity from sunlight. The photovoltaic cells within a solar panel, known as solar cells, contain semiconductors that generate Direct Current electricity in response to light. This is known as the photovoltaic effect, a natural phenomenon discovered by Edmond Becquerel in 1839.
Solar panel output varies depending on the material from which the solar cells are made. The two most common types of solar panels are monocrystalline and polycrystalline, both of which are made from silicon cells. The third most common type of solar panel is thin-film.
Monocrystalline solar panels made from one piece of silicon offer up to 25% efficiency, whereas polycrystalline solar panels containing multiple silicon crystals only offer 13% to 16% efficiency.
Thin-film solar panels, such as those made from cadmium telluride or CIGS (Copper Indium Gallium Selenide), are made by applying a layer of photovoltaic material to a flexible base layer. Thin film efficiency varies considerably by subtype but generally falls within a range of 8-20%.
The output of a solar panel is determined by its power rating, not by the size of the solar panel or the number of solar cells that it contains. The power rating of solar panels specifies the amount of electricity that they are able to produce under ideal conditions, but this figure is determined in a laboratory setting and doesn’t reflect their actual output in different locations and weather conditions.
A small solar panel with a high power rating is able to produce the same amount of energy as a solar panel, which is physically larger but has a lower power rating, so it is a fallacy that a greater surface indicates a greater capacity to produce electricity.
Are all types of Solar Panel Recyclable?
Yes, all types of solar panels are recyclable because both thin-film solar panels and silicon solar panels contain glass, plastic, aluminum, and other metals that can be removed and reused. Silicon-based solar panels undergo a recycling process different from that of thin-film solar panels. Silicon-based monocrystalline and polycrystalline solar modules are recycled by a chemical process called etching, which creates silicon wafers from individual PV cells, whereas thin-film solar modules are recycled by removing the semiconductor material and shredding it in a special machine called a hammermill.
Separating the components in a solar module to recycle them is not an easy process for any of the solar panel types, so not 100% of the raw material is reused. Additionally, solar panels contain hazardous materials like cadmium, which need to be handled carefully to avoid damage to human health or the environment.
What are the parts of the Solar Panel that are Recyclable?
The recyclable parts of a solar panel are the metal frame (typically aluminum), the glass cover, the copper wires, the silicon solar cells, and the plastic junction box. The glass cover is the largest part of a solar panel, accounting for 75% of its weight, and the easiest component to recycle.
Technically, all parts of a solar panel are recyclable, using different processes. Metal, glass, and copper are recycled from solar panels by removing the components and melting them down to create raw material for new products, whereas silicon is removed in wafers, melted down, cast into a slab, and then sliced or reshaped to create new products.
It is difficult to dispose of monocrystalline or polycrystalline solar panels properly because no recycling programs in the US accept silicon, so the only way to get rid of silicon-based solar modules is to bring them to a specialized silicon recycling plant.
Solar panel waste is an issue in the US because the government financially incentivizes residents to install solar energy while failing to provide a system for solar panel disposal, resulting in solar panels ending up in landfills, according to C. Watson in the research paper "Solving Solar: How Past Policy Collides With Future Technology" published in Texas A&M Law Review journal in 2023.
How to Recycle Solar Panels?
The four main steps to recycle solar panels are listed below.
1. The aluminum frame is taken apart
The first step in recycling solar panels is to dismantle the outer components, which are the aluminum frame, cables, and junction boxes. To take the aluminum frame off a solar panel, remove the module from the bracket attaching it to the mount (on the roof or on the ground), use a drill to remove all of the screws from the frame, use a heat gun to melt the adhesive holding the frame to the glass, slip a flathead screwdriver under the lip of the frame to pry it gently from the glass and repeat for each side of the frame.
Solar panel recycling plants use a machine called an automated frame separator to disassemble solar panels mechanically, which is quicker and easier than taking the aluminum frame apart by hand.
2. The glass is separated out
The purpose of the glass sheet on the front of solar panels is to protect the solar cells and internal wiring from damage. Removing the glass from the solar panel is a pivotal part of solar panel recycling, to ensure the material is not wasted.
One way to separate the glass from a solar panel is to apply heat, which weakens the encapsulant holding the layers together and causes the components to expand at different rates so they are easier to separate.
Heating a silicon-based solar panel reduces the amount of force necessary to remove the frame by more than half, according to Kamano et al. in the research article “Glass separation process for recycling of solar photovoltaic panels by microwave heating” presented at the 3rd International Conference on Energy and Power in 2022.
Applying heat to a solar panel is an effective way to separate the glass from the module, but it is typically used in conjunction with mechanical and chemical treatment.
Mechanical methods such as crushing, grinding, and vibration are used to separate the glass from the solar panel, producing fragments of glass that undergo further treatment to be refined and cleaned of resin, according to Pagnanelli et al. in the research article "Physical and chemical treatment of end of life panels: An integrated automatic approach viable for different photovoltaic technologies" published in the Waste Management Journal in 2016.
The aim of chemical treatment is to dissolve the resin holding the layer of glass and the layer of solar cells together without damaging the solar cell in order to recycle the solar panel. Silicon-based solar panels, monocrystalline and polycrystalline, are sealed using a rubber-like substance called ethylene-vinyl acetate (EVA).
Chemicals like nitric acid and organic solvents are used to dissolve the EVA and recover the solar cell, as described by Kim & Lee in the research article “Dissolution of ethylene vinyl acetate in crystalline silicon PV modules using ultrasonic irradiation and organic solvent” published in the Solar Energy Materials and Solar Cells journal in 2012.
3. The cells are processed at 900 degrees Fahrenheit
The solar cells undergo thermal processing once they have been taken out of the solar panel, to remove any remaining residue from adhesives or encapsulants. The PV cells are heated to 900 degrees Fahrenheit (around 500 degrees Celcius) to break the bonds between the silicon cells and any remaining metal or plastic particles.
The purpose of heating the solar cells is to purify them and isolate the silicon, the valuable material, for further treatment before being recycled. Recovering the silicon from solar panels is essential for the solar industry to be sustainable because it allows solar panel manufacturers to use recycled silicon to produce new PV modules and decreases their reliance on mining minerals from the earth to create new silicon.
4. The silicon wafers are etched away, then melted into workable slabs
The layers of a solar panel have to be separated (using thermal, mechanical, and chemical methods) before it is viable to etch silicon wafers from them. Silicon wafers are recovered from solar panels by etching, a technique that uses chemicals to dissolve the remnants of encapsulants, adhesives, and metals on the surface of the solar cell.
The best chemicals to etch solar panels for solar wafers are nitric acid, potassium hydroxide, and etching paste containing phosphoric acid because they extract all remaining silver, aluminum, and silicon nitride, according to Park & Park in the research article “Wet etching processes for recycling crystalline silicon solar cells from end-of-life photovoltaic modules” published in the Royal Society of Chemistry journal in 2014.
Research is ongoing to develop a method of etching solar cells that produces recycled wafers of identical quality, in terms of thickness and resistance, to virgin commercial wafers. Once the silicon wafers are recovered from solar panels, they are melted down, cast into large slabs, and sliced or reshaped to create different products.
What is the benefit of Recycling a Solar Panel?
Recycling solar panels has a positive effect on the environment because reusing raw materials from discarded PV modules decreases the number of landfills and reduces the amount of minerals being mined to create virgin silicon. The purpose of having a circular economy in the solar industry is to make it sustainable, reusing components from solar panels that are ‘burnt out’ or irreparably damaged to extend their lifecycle and prevent them from becoming waste in landfills.
Recycling end-of-life solar panels in the United States (to keep the raw material they contain in circulation) decreases the country’s reliance on importing PV components to meet the domestic demand for solar energy, according to Curtis et al. in the report “Solar Photovoltaic Module Recycling: A Survey of U.S. Policies and Initiatives” published by the National Renewable Energy Laboratory in 2021.
What is the risk of Recycling a Solar Panel?
The main risk of recycling a solar panel is improper handling, resulting in potential harm to human health or the environment as a result of hazardous chemicals. Solar panels contain hazardous chemicals such as cadmium, which can leach out. Other materials that cause serious harm to human health if they make their way into the groundwater supply are silicon, lead, and arsenic. For this reason, it's crucial that solar panel recycling is executed according to strict procedures and processes.
Another risk of recycling solar panels is damaging the module in the process. Solar panels contain several layers of material, tightly secured together, which require time and skill to separate without applying excessive force. The ethylene-vinyl acetate (EVA), which holds the layers of the solar panel together to protect it from the elements, known as polymer or resin, makes taking the module apart difficult, expensive, and time-consuming.
Which nation has the best regulations for Solar Panel Recycling?
The European Union adheres to specific waste regulations that require photovoltaic manufacturers to recycle 75% of solar panel waste and recover 80% of the raw materials within them, according to revisions made to the Waste Electrical and Electronic Equipment regulation in 2018. Europe is ahead of the curve when it comes to legislation for photovoltaic waste, whereas the United States lacks sufficient federal regulation for recycling solar waste.
Are there regulations in handling or disposing of Solar Panels' hazardous waste?
Yes, there are regulations for disposing of solar panels in the US, including the Hazardous Waste Regulations and the Resource Conservation and Recovery Act. The disposal of solar panels falls under hazardous waste regulations in the US, insofar as solar panels are given the status of ‘solid waste’ when they are discarded. The Resource Conservation and Recovery Act lays out which waste is considered hazardous, so discarded solar panels containing heavy metals are flagged as toxic due to the risk of these substances leaching into the soil and polluting the groundwater. The aluminum frame and glass cover of solar panels are recycled at general facilities before hazardous waste from the remaining solar panels is sent to landfills or burned.
Are there companies that offer Solar Panel Recycling?
Yes, there are companies that offer solar panel recycling in the US, like CEM, Cleanlites Recycling, Dynamic Lifecycle Innovations and Echo Environmental. There are 26 solar panel recycling companies included on the Solar Photovoltaic Manufacturing Map created by the US Department of Energy, indicating that almost half of the states have no option for solar panel recycling.
What is the common challenge Solar Panel Recycling faces?
Recycling solar panels is not a quick or easy job. Solar panels are time-consuming to disassemble, meaning solar recycling companies have to invest in specialized equipment and workers, notwithstanding the fact that products made from recycled solar panel components are typically lower quality than the original products. Solar recycling companies have to spend a lot of time and money to separate the components of a solar panel, at a low profit margin.
What happens to the Solar Panels' waste?
In the US, the waste from solar panels is classified as “solid waste” by the government, and sent to landfill. This is largely due to the limited options for solar panel recycling in the US and the lack of available services.
Sending solar panels to landfills at end-of-life is problematic because they contain toxic substances like lead and cadmium, which cause problems when they leach into the soil surrounding the dump. Cadmium contamination occurs when solar panels are discarded in landfills and the chemicals inside them leach into the ground.
Cadmium contamination is a problem because cadmium is a toxic heavy metal that has harmful effects on human health and the environment. When cadmium leaks into the soil from discarded solar panels in landfills, it carries the potential to contaminate groundwater and surface water sources.
This contamination can then enter the food chain, as plants absorb cadmium from the soil, and animals and humans consume these plants. Long-term exposure to cadmium leads to serious health issues, including kidney damage, lung damage, and cancer. Cadmium is a persistent pollutant, meaning it remains in the environment for a long time, continuing to pose a threat to ecosystems and human health.
Nearly 10 million metric tons of solar panel waste is expected to accumulate between 2030 and 2060, based on the average lifespan of a solar panel, the number of solar systems in the US in 2024, and how much the demand for solar energy is expected to increase, according to Domínguez & Geyer in the research article “Photovoltaic waste assessment of major photovoltaic installations in the United States of America” published in the Renewable Energy journal in 2018.
What happens to Solar Panels at End-of-Life?
When solar panels stop generating energy, at the end of their lifecycle, they are either discarded in landfills or recycled into new solar components. Despite investing in solar energy, and providing substantial financial incentives for residents to install solar systems, the United States lacks a mainstream system for solar panel recycling. Solar panel recycling facilities are able to salvage the aluminum, glass and copper before the rest of the solar panel’s components are sent to landfill.
What is the average lifespan of a Solar Panel?
The average lifespan of a solar panel ranges from 25 to 30 years, but their efficiency declines over time, and they gradually produce less electricity, known in the solar industry as ‘degradation.’ The quality of the solar panel determines the rate at which it will degrade. The average solar panel degrades at 0.5% per year, so it is still able to produce 90% of its original output after 20 years of use.
Are Solar Panels worth recycling?
Yes, solar panels are worth recycling because solar modules contain valuable raw materials like glass and aluminum, which are wasted in landfills when the components are not reused. Another factor that makes solar panels worth recycling is that the toxic materials they contain are bad for landfills, leaking into and damaging the surrounding environment when they are discarded.
Is it costly to Recycle Solar Panels?
Yes, it is costly to recycle solar panels, at around $45 to recycle one solar panel and $5 to send one solar panel to a landfill, according to the Office of Efficiency & Renewable Energy at the US Department of Energy. Their report, entitled “Solar Energy Technologies Office
Photovoltaics End-of-Life Action Plan, was published in 2022. It is expensive to recycle solar panels in the US, notwithstanding that most of the material from defective solar panels is not even reclaimed when they are recycled, which is why only 10% of solar panels are recycled instead of being dumped in landfill, according to report “Solar Photovoltaics Supply Chain Deep Dive Assessment” published by the US Department of Energy in 2022.